• A serial offender made its latest appearance – as several readers noticed – when we misused the word prone in a caption that described the sons of Egypt's former president observing court proceedings in Cairo with their "prone father". To be prone, a person must lie face down. Hosni Mubarak was on his back – "supine", readers said, or "recumbent" (A moment to savour – but outside the bloodshed went on, 4 August, page 6).

• The payoff line in a piece about wrong prophecies – Why failed forecasts aren't the end of world, 21 May, page 3 – said people would do well to "heed the advice of Casey Stengel, the baseball legend, who insisted that we should 'never make predictions, especially about the future'". Actually, the origin of this saying is disputed. It has also been laid at the doorstep of Hollywood's Sam Goldwyn, baseball player Yogi Berra, and Danish physicist Niels Bohr (1885-1962). A letter in the Economist in 2007 added: "It is said that ... Bohr used to quote this saying to illustrate the differences between Danish and Swedish humour. Bohr himself usually attributed the saying to Robert Storm Petersen (1882-1949), also called Storm P, a Danish artist and writer. However, the saying did not originate from Storm P. The original author remains unknown (although Mark Twain is often suggested)."